Cut each zucchini in half lengthwise; scoop out pulp, leaving a 1/4-inch-thick shell. Place zucchini halves, cut sides up, in a shallow roasting pan. Sprinkle with 1/2 teaspoon salt.
Preheat oven to 375°.
Cook potato in boiling water 2 minutes or until crisp-tender; drain.
Heat butter and oil in a nonstick skillet over medium-high heat until butter melts. Add onion, ginger, garlic, and chile, and sauté 3 minutes. Stir in flour and next 4 ingredients (flour through cumin). Cook over medium-low heat 5 minutes, stirring frequently. Stir in 3/4 teaspoon salt, potato, peas, and cilantro.
Pat zucchini dry with paper towels; spoon about 1/3 cup potato mixture into each zucchini half. Cover and bake at 375° for 20 minutes or until zucchini is tender.